The objective of this study is to determine if complete or partial sinoaortic denervation in the subhuman primate (Papio anubis) produces a neurogenic hypertension. Specific objectives are to determine peripheral denervation of the carotid sinus, aortic baroreceptors or both leads to a sustained increase in arterial pressure and an increased lability in the unrestrained tethered baboon. The arterial pressure and lability of arterial pressure will be determined by measuring denervation of the arterial baroreceptors. Comparison will be made of the mean 24 hr arterial pressure and standard deviation before and various times after denervation. In addition to evaluating the stability of arterial pressure from the stand and deviation of the 24 hr arterial pressure measurements, we will assess the arterial baroreflex sensitivity by determining the heart rate response to a change in arterial pressure. Plasma catecholamines concentration and plasma renin activity will be determined in the basal state and during drug induced pressure changes before and various times following denervation. These studies will be the first to determine the role of arterial baroreceptors in the regulation of arterial pressure in the subhuman primate.